From 3628ceec480c3d8fa9673f80f781eb1153fb9e1f Mon Sep 17 00:00:00 2001
From: Enrico Forestieri <forenr@lyx.org>
Date: Wed, 8 Nov 2017 08:44:00 +0100
Subject: [PATCH] Fix #10778 (issue with CJK and language nesting)

When using CJK, don't try to close a language that was never
opened before, such as when it is the main language.
---
 src/Paragraph.cpp    | 1 +
 src/output_latex.cpp | 8 ++++++++
 src/output_latex.h   | 7 +++++++
 status.22x           | 2 ++
 4 files changed, 18 insertions(+)

diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index 48d0e1737f..3a9dd6ee27 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -2486,6 +2486,7 @@ void Paragraph::latex(BufferParams const & bparams,
 		bool const using_begin_end = runparams.use_polyglossia ||
 						!lang_end_command.empty();
 		if (!running_lang.empty() &&
+		    (!using_begin_end || running_lang == openLanguageName()) &&
 		    font.language()->encoding()->package() == Encoding::CJK) {
 				string end_tag = subst(lang_end_command,
 							"$$lang",
diff --git a/src/output_latex.cpp b/src/output_latex.cpp
index eac0a93f52..5e49456929 100644
--- a/src/output_latex.cpp
+++ b/src/output_latex.cpp
@@ -527,6 +527,14 @@ void popLanguageName()
 }
 
 
+string const & openLanguageName()
+{
+	OutputState * state = getOutputState();
+
+	return openLanguageName(state);
+}
+
+
 void latexArgInsets(Paragraph const & par, otexstream & os,
 	OutputParams const & runparams, Layout::LaTeXArgMap const & latexargs, string const & prefix)
 {
diff --git a/src/output_latex.h b/src/output_latex.h
index 61a9354f6c..fd3e805fe0 100644
--- a/src/output_latex.h
+++ b/src/output_latex.h
@@ -39,6 +39,13 @@ void pushLanguageName(std::string const & lang, bool localswitch = false);
  */
 void popLanguageName();
 
+/** Return a reference to the last active language opened with
+    polyglossia or when using begin/end commands. If none or when
+    using babel with only a begin command, return a reference to
+    an empty string.
+ */
+std::string const & openLanguageName();
+
 /** Export optional and required arguments of the paragraph \p par.
     Non-existing required arguments are output empty: {}.
  */
diff --git a/status.22x b/status.22x
index 0f1e6e5668..a25c7cfb80 100644
--- a/status.22x
+++ b/status.22x
@@ -71,6 +71,8 @@ What's new
   (2013ff.) instead of vietnam.ldf that was shipped with vntex previously
   (bug 10743).
 
+- Fix issue with language nesting when using Asian languages (bug 10778).
+
 
 * LYX2LYX